1. Technical Field
The present disclosure is directed to multiport connector assemblies for a telecommunication connector system that are designed to reduce crosstalk noise between adjacent ports through advantageous electrical isolation design(s).
2. Background Art
As Unshielded Twisted Pair (“UTP”) cabling continues to be an essential choice of media transmission, new and improved methods must be employed meet the requirements of the transmitting data source. UTP cable is a popular and widely used type of data transfer media. UTP cable is a very flexible, low cost media, and can be used for either voice or data communications. In fact, UTP cable is in some respects the de facto standard for Local Area Networks (LANs), and other in-building voice and data communications applications. In an UTP, a pair of copper wires generally forms the twisted pair. For example, a pair of copper wires with diameters of 0.4-0.8 mm may be twisted together and wrapped with a plastic coating to form an UTP. The twisting of the wires increases the noise immunity and reduces the bit error rate (BER) of the data transmission to some degree. In addition, using two wires, rather than one, to carry each signal permits differential signaling to be utilized. Differential signaling is generally immune to the effects of external electrical noise.
The non-use of cable shielding (e.g., a foil or braided metallic covering) in fabricating UTP cable generally increases the effects of outside interference, but also results in reduced cost, size, and installation time of the cable and associated connectors. Additionally, non-use of cable shielding in UTP fabrication generally eliminates the possibility of ground loops (i.e., current flowing in the shield because of the ground voltage at each end of the cable not being the same). Ground loops may give rise to a current that induces interference within the cable, interference against which the shield was intended to protect.
The wide acceptance and use of UTP cable for data and voice transmission is primarily due to the large installed base, low cost and ease of new installation. Another important feature of UTP is that it is used for varied applications, such as for Ethernet, Token Ring, ATM, EIA-232, DSL, analog telephone (POTS), and other types of communication. This flexibility allows the same type of cable/system components (such as data jacks, plugs, cross-patch panels, and patch cables) to be used for an entire building, unlike shielded twisted pair media (STP). At present, UTP cabling is being utilized for systems having increasingly higher data rates. Since demands on networks using UTP systems (e.g., 100 Mbit/s and 1000 Mbit/s transmission rates) have increased, it has become necessary to develop industry standards for higher system bandwidth performance.
UTP systems such as 100 Mbit/s and 1000 Mbit/s transmission rates have produced requirements and specification for cabling transmission such as TIA 568B.2-1, which is basically the standard for category 6 cabling systems. The bandwidth requirements are 1 to 250 MHz. The main parameters are near-end crosstalk (NEXT), far-end crosstalk (FEXT), equal level FEXT, return loss (RL), attenuation, as well as, crosstalk Powersum parameters (PSNEXT) and PSELFEXT. From these parameters, one of the major contributors to system performance is control of NEXT. What began as the need for connecting hardware to provide NEXT loss of less than −36 dB at 16 MHz, has evolved to −54 dB at 100 MHz and −46 dB at 250 MHz for category 6 systems with future requirements up to 500 MHz. For any data transmission event, a received signal will consist of a transmission signal modified by various distortions. The distortions are added by the transmission system, along with additional unwanted signals that are inserted somewhere between transmission and reception. The unwanted signals are referred to as noise. Noise is the major limiting factor in the performance of today's communication systems. Problems that arise from noise include data errors, system malfunctions, and loss of the desired signals.
Generally, crosstalk noise occurs when a signal from one source is coupled to another line. Crosstalk noise could also be classified as electromagnetic interference (EMI). EMI occurs through the radiation of electromagnetic energy. Electromagnetic energy waves can be derived by Maxwell's wave equations. These equations are basically defined using two components: electric and magnetic fields. In unbounded free space, a sinusoidal disturbance propagates as a transverse electromagnetic wave. This means that the electric field vectors are perpendicular to the magnetic field vectors that lie in a plane perpendicular to the direction of the wave. NEXT noise is the effect of near-field capacitive (electrostatic) and inductive (magnetic) coupling between source and victim electrical transmissions.
Typical Category 5e, 6 and most likely C6 augmented connecting hardware will incorporate signal feedback techniques called compensation reactance. The use of compensation can decrease the internal noise associated with NEXT and FEXT, but it can also increase the connecting hardware external noise sources called alien near-end crosstalk (ANEXT) and alien far-end crosstalk (AFEXT), and the power summation of these noises.
ANEXT is near-end crosstalk noise that couples from one cabling media to an adjacent cabling media, measured at the near-end or transmitter. AFEXT is far-end crosstalk noise that couples from one cabling media to an adjacent cabling media, measured at the far-end or receiver. Power sum alien near-end crosstalk (PSANEXT) loss is a combination of signal coupling from multiple near-end disturbing cabling pairs into a disturbed pair of a neighboring cabling or part thereof, measured at the near-end. Power sum alien far-end crosstalk (PSAFEXT) loss is a combination of signal coupling from multiple far-end disturbing cabling pairs into a disturbed pair of a neighboring cabling or part thereof, measured at the far-end. IEEE 802.3 an 10 Gigabit Ethernet (10 Gbe) and the TIA TR42.7 working groups have identified ANEXT and AFEXT as major noise problems that can effect proper 10 Gbe operation over UTP cabling systems, with ANEXT being the most impactful of the two. The initial ANEXT requirement for UTP cabling system, also called “Augmented Category 6 UTP,” is shown in Table 1 below:
TABLE 1ANEXT from TIA 568B.2-A10 draft for AugmentedCategory 6 (100 meters channel link cabling)MHzdB10−70100−60250−54400−51500−49.5
Connecting hardware systems that will run 10 Gbe data signals must be designed to meet traditional Category 6, as well as recognized additional 10 Gbe UTP cabling parameters. Due to the adjacency of connecting hardware in a cabling system, ANEXT and AFEXT noise sources will necessarily be present.
One approach to control ANEXT is the usage of a fully shielded cabling system, also called Foiled Twisted pair or Screened Twisted pair (ScTP). Typical FTP cabling system incorporates metallic shields that are electrically mated to ground by the transmitting source and/or by the equipment rack ground system. The connector shields are electrically connected together, either externally by mated shield contact or internally by the PCB connection. FTP systems are an effective media for reduction of ANEXT and AFEXT noise sources. Other methods for reducing ANEXT and AFEXT involve mitigation techniques, such as increasing connector spacing arrangement. Utilizing FTP or mitigation cabling methods provide various issues and increase complexities. In addition, FTP systems are considerably more expensive in material and installation cost. As previously discussed, another issue with FTP is proper installation of system grounds. Poor system grounding can create unwanted ground loops that could lead to increased system noise internally to the transmitter. Mitigation of connectors in many cases is not an option since standard wall outlets (i.e., single gang electrical boxes) and 1 rack unit (typ. 1.5 inch) high mount panels are spaced limited based on prior standards.